The Experts below are selected from a list of 420 Experts worldwide ranked by ideXlab platform
J-f Masson - One of the best experts on this subject based on the ideXlab platform.
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low temperature bitumen stiffness and viscous paraffinic nano and micro domains by cryogenic afm and pdm
Journal of Microscopy, 2007Co-Authors: J-f Masson, V Leblond, J Margeson, S BundalopercAbstract:Summary In an effort to better understand the structure and behaviour of bitumen in low temperature, we describe the first use of cryogenic atomic force microscopy and phase detection microscopy to characterize bitumen nano- and micro-structures. The results were interpreted in light of glass transition temperatures (Tgs) for bitumen fractions. The domains visible by microscopy, the catana, peri and para phases, were attributed to domains rich in asphaltenes, Naphthene and polar Aromatics, and saturates, respectively. Between −10°C and −30°C, atomic force microscopy images revealed topographic features not visible in atomic force microscopy images acquired at room temperature. According to phase detection microscopy and Tgs, the features were assigned to viscous unfrozen saturates. Upon cooling to −72°C, unfrozen domains of 20–400 nm were observed. These domains were found in the paraphase rich in saturates and in the periphase rich in Naphthene Aromatics and polar Aromatics. The findings indicate that new viscous domains form upon cooling to low temperatures owing to phase segregation, and that some bitumens are never entirely rigid in low temperatures.
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Low-temperature bitumen stiffness and viscous paraffinic nano- and micro-domains by cryogenic AFM and PDM
Journal of Microscopy, 2007Co-Authors: J-f Masson, V Leblond, J Margeson, Slaðana Bundalo-percAbstract:In an effort to better understand the structure and behaviour of bitumen in low temperature, we describe the first use of cryogenic atomic force microscopy and phase detection microscopy to characterize bitumen nano- and micro-structures. The results were interpreted in light of glass transition temperatures (T(g)s) for bitumen fractions. The domains visible by microscopy, the catana, peri and para phases, were attributed to domains rich in asphaltenes, Naphthene and polar Aromatics, and saturates, respectively. Between -10 degrees C and -30 degrees C, atomic force microscopy images revealed topographic features not visible in atomic force microscopy images acquired at room temperature. According to phase detection microscopy and T(g)s, the features were assigned to viscous unfrozen saturates. Upon cooling to -72 degrees C, unfrozen domains of 20-400 nm were observed. These domains were found in the paraphase rich in saturates and in the periphase rich in Naphthene Aromatics and polar Aromatics. The findings indicate that new viscous domains form upon cooling to low temperatures owing to phase segregation, and that some bitumens are never entirely rigid in low temperatures.
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Bitumen morphologies by phase-detection atomic force microscopy.
Journal of microscopy, 2006Co-Authors: J-f Masson, V Leblond, J MargesonAbstract:Summary Bitumen is a complex mixture of hydrocarbons for which microstructural knowledge is incomplete. In an effort to detail this microstructure, 13 bitumens were analysed by phase-detection atomic force microscopy. Based on morphology, the bitumens could be classified into three distinct groups. One group showed fine domains down to 0.1 microm, another showed domains of about 1 microm, and a third group showed up to four different domains or phases of different sizes and shapes. No correlation was found between the atomic force microscopy morphology and the composition based on asphaltenes, polar Aromatics, Naphthene Aromatics and saturates. A high correlation was found between the area of the 'bee-like' structures and the vanadium and nickel content in bitumen, and between the atomic force microscopy groups and the average size of molecular planes made of fused Aromatics. The morphology and the molecular arrangements in bitumen thus appear to be partly governed by the molecular planes and the polarity defined by metallic cations.
J Margeson - One of the best experts on this subject based on the ideXlab platform.
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low temperature bitumen stiffness and viscous paraffinic nano and micro domains by cryogenic afm and pdm
Journal of Microscopy, 2007Co-Authors: J-f Masson, V Leblond, J Margeson, S BundalopercAbstract:Summary In an effort to better understand the structure and behaviour of bitumen in low temperature, we describe the first use of cryogenic atomic force microscopy and phase detection microscopy to characterize bitumen nano- and micro-structures. The results were interpreted in light of glass transition temperatures (Tgs) for bitumen fractions. The domains visible by microscopy, the catana, peri and para phases, were attributed to domains rich in asphaltenes, Naphthene and polar Aromatics, and saturates, respectively. Between −10°C and −30°C, atomic force microscopy images revealed topographic features not visible in atomic force microscopy images acquired at room temperature. According to phase detection microscopy and Tgs, the features were assigned to viscous unfrozen saturates. Upon cooling to −72°C, unfrozen domains of 20–400 nm were observed. These domains were found in the paraphase rich in saturates and in the periphase rich in Naphthene Aromatics and polar Aromatics. The findings indicate that new viscous domains form upon cooling to low temperatures owing to phase segregation, and that some bitumens are never entirely rigid in low temperatures.
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Low-temperature bitumen stiffness and viscous paraffinic nano- and micro-domains by cryogenic AFM and PDM
Journal of Microscopy, 2007Co-Authors: J-f Masson, V Leblond, J Margeson, Slaðana Bundalo-percAbstract:In an effort to better understand the structure and behaviour of bitumen in low temperature, we describe the first use of cryogenic atomic force microscopy and phase detection microscopy to characterize bitumen nano- and micro-structures. The results were interpreted in light of glass transition temperatures (T(g)s) for bitumen fractions. The domains visible by microscopy, the catana, peri and para phases, were attributed to domains rich in asphaltenes, Naphthene and polar Aromatics, and saturates, respectively. Between -10 degrees C and -30 degrees C, atomic force microscopy images revealed topographic features not visible in atomic force microscopy images acquired at room temperature. According to phase detection microscopy and T(g)s, the features were assigned to viscous unfrozen saturates. Upon cooling to -72 degrees C, unfrozen domains of 20-400 nm were observed. These domains were found in the paraphase rich in saturates and in the periphase rich in Naphthene Aromatics and polar Aromatics. The findings indicate that new viscous domains form upon cooling to low temperatures owing to phase segregation, and that some bitumens are never entirely rigid in low temperatures.
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Bitumen morphologies by phase-detection atomic force microscopy.
Journal of microscopy, 2006Co-Authors: J-f Masson, V Leblond, J MargesonAbstract:Summary Bitumen is a complex mixture of hydrocarbons for which microstructural knowledge is incomplete. In an effort to detail this microstructure, 13 bitumens were analysed by phase-detection atomic force microscopy. Based on morphology, the bitumens could be classified into three distinct groups. One group showed fine domains down to 0.1 microm, another showed domains of about 1 microm, and a third group showed up to four different domains or phases of different sizes and shapes. No correlation was found between the atomic force microscopy morphology and the composition based on asphaltenes, polar Aromatics, Naphthene Aromatics and saturates. A high correlation was found between the area of the 'bee-like' structures and the vanadium and nickel content in bitumen, and between the atomic force microscopy groups and the average size of molecular planes made of fused Aromatics. The morphology and the molecular arrangements in bitumen thus appear to be partly governed by the molecular planes and the polarity defined by metallic cations.
V Leblond - One of the best experts on this subject based on the ideXlab platform.
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low temperature bitumen stiffness and viscous paraffinic nano and micro domains by cryogenic afm and pdm
Journal of Microscopy, 2007Co-Authors: J-f Masson, V Leblond, J Margeson, S BundalopercAbstract:Summary In an effort to better understand the structure and behaviour of bitumen in low temperature, we describe the first use of cryogenic atomic force microscopy and phase detection microscopy to characterize bitumen nano- and micro-structures. The results were interpreted in light of glass transition temperatures (Tgs) for bitumen fractions. The domains visible by microscopy, the catana, peri and para phases, were attributed to domains rich in asphaltenes, Naphthene and polar Aromatics, and saturates, respectively. Between −10°C and −30°C, atomic force microscopy images revealed topographic features not visible in atomic force microscopy images acquired at room temperature. According to phase detection microscopy and Tgs, the features were assigned to viscous unfrozen saturates. Upon cooling to −72°C, unfrozen domains of 20–400 nm were observed. These domains were found in the paraphase rich in saturates and in the periphase rich in Naphthene Aromatics and polar Aromatics. The findings indicate that new viscous domains form upon cooling to low temperatures owing to phase segregation, and that some bitumens are never entirely rigid in low temperatures.
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Low-temperature bitumen stiffness and viscous paraffinic nano- and micro-domains by cryogenic AFM and PDM
Journal of Microscopy, 2007Co-Authors: J-f Masson, V Leblond, J Margeson, Slaðana Bundalo-percAbstract:In an effort to better understand the structure and behaviour of bitumen in low temperature, we describe the first use of cryogenic atomic force microscopy and phase detection microscopy to characterize bitumen nano- and micro-structures. The results were interpreted in light of glass transition temperatures (T(g)s) for bitumen fractions. The domains visible by microscopy, the catana, peri and para phases, were attributed to domains rich in asphaltenes, Naphthene and polar Aromatics, and saturates, respectively. Between -10 degrees C and -30 degrees C, atomic force microscopy images revealed topographic features not visible in atomic force microscopy images acquired at room temperature. According to phase detection microscopy and T(g)s, the features were assigned to viscous unfrozen saturates. Upon cooling to -72 degrees C, unfrozen domains of 20-400 nm were observed. These domains were found in the paraphase rich in saturates and in the periphase rich in Naphthene Aromatics and polar Aromatics. The findings indicate that new viscous domains form upon cooling to low temperatures owing to phase segregation, and that some bitumens are never entirely rigid in low temperatures.
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Bitumen morphologies by phase-detection atomic force microscopy.
Journal of microscopy, 2006Co-Authors: J-f Masson, V Leblond, J MargesonAbstract:Summary Bitumen is a complex mixture of hydrocarbons for which microstructural knowledge is incomplete. In an effort to detail this microstructure, 13 bitumens were analysed by phase-detection atomic force microscopy. Based on morphology, the bitumens could be classified into three distinct groups. One group showed fine domains down to 0.1 microm, another showed domains of about 1 microm, and a third group showed up to four different domains or phases of different sizes and shapes. No correlation was found between the atomic force microscopy morphology and the composition based on asphaltenes, polar Aromatics, Naphthene Aromatics and saturates. A high correlation was found between the area of the 'bee-like' structures and the vanadium and nickel content in bitumen, and between the atomic force microscopy groups and the average size of molecular planes made of fused Aromatics. The morphology and the molecular arrangements in bitumen thus appear to be partly governed by the molecular planes and the polarity defined by metallic cations.
Michael L Greenfield - One of the best experts on this subject based on the ideXlab platform.
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Chemical compositions of improved model asphalt systems for molecular simulations
Fuel, 2014Co-Authors: Michael L GreenfieldAbstract:Abstract New chemical compositions of model asphalts to represent the AAA-1, AAK-1 and AAM-1 asphalts of the Strategic Highway Research Program are proposed to enable molecular simulations that can further an understanding of asphalt physical, rheological and mechanical properties. Molecules for the three model asphalt systems were selected from compounds that had been identified in petroleum and geochemistry studies available in the literature. Choosing larger molecules than in past model asphalt systems improved agreement with size characterization data. The molecules were classified into saturates, Naphthene Aromatics, polar Aromatics and asphaltenes using the Hansen solubility parameters, size and functional groups. Quantum mechanics was used for determining force field parameters and partial charges from electrostatic potential. Classical molecular dynamics simulations were used to calculate physical properties for one of the model asphalt systems. Densities for the model AAA-1 asphalt system are closer to experimental data compared to previous model systems, with good agreement for thermal expansion coefficient. These studies and results provide an improved tool for relating asphalt chemical compositions to rheological and mechanical properties.
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Analyzing Properties of Model Asphalts Using Molecular Simulation
2007Co-Authors: Liqun Zhang, Michael L GreenfieldAbstract:Molecular simulations have been used to estimate the properties of three-component mixtures whose constituents were chosen to represent the chemical families found in paving asphalts. Naphthene Aromatics and saturates were represented by 1,7-dimethylnaphthalene and n-C22, respectively. Two different asphaltene model structures were considered. The first has a large aromatic core with a few short side chains; the second contains a moderate size aromatic core with larger branches. Both types have been proposed in the recent literature based on experimental characterizations of asphaltene fractions. Properties calculated from atomistic molecular simulations of the mixtures include density, isothermal compressibility (inverse of bulk modulus), and zero shear viscosity. The thermodynamic properties suggest a high frequency glass transition above 25oC for both model mixtures. The mixture based on the more aromatic asphaltene shows a more pronounced transition and has a higher bulk modulus. The calculated viscosity at elevated temperatures is somewhat smaller than that of real asphalts. For a polymer-modified model asphalt, the calculations are consistent with increases in viscosity and bulk modulus.
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Analyzing properties of model asphalts using molecular simulation
Energy & Fuels, 2007Co-Authors: Liqun Zhang, Michael L GreenfieldAbstract:Molecular simulations have been used to estimate the properties of three-component mixtures whose constituents were chosen to represent the chemical families found in paving asphalts. Naphthene Aromatics and saturates were represented by 1,7-dimethylnaphthalene and n-C22, respectively. Two different asphaltene model structures were considered. The first has a large aromatic core with a few short side chains; the second contains a moderate size aromatic core with larger branches. Both types have been proposed in the recent literature based on experimental characterizations of asphaltene fractions. Properties calculated from atomistic molecular simulations of the mixtures include density and isothermal compressibility (inverse of bulk modulus). The thermodynamic properties suggest a high-frequency glass transition above 25 °C for both model mixtures. The mixture based on the more aromatic asphaltene shows a more pronounced transition and has a higher bulk modulus. For a polymer-modified model asphalt, the c...
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Testing Model Asphalt System Modification Using Molecular Simulation
2006Co-Authors: Michael L Greenfield, Liqun ZhangAbstract:One original objective of this work was to study a test case of adding a polymer modifier to the model asphalts developed earlier. A second objective was to expand the calculated results from thermodynamics properties, such as density, heat capacity, and compressibility, to transport properties, such as viscosity and modulus. Two additional objectives were recognized as the project began: (1) to repeat the original model asphalt calculations to include properly a parameter that affects planarity of aromatic groups, and (2) to expand mixture compositions to include chemical components of intermediate polarity between Naphthene Aromatics and asphaltenes, i.e., resin-like compounds. The different chapter in this report will illustrate the progress and success achieved towards each objective.
Slaðana Bundalo-perc - One of the best experts on this subject based on the ideXlab platform.
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Low-temperature bitumen stiffness and viscous paraffinic nano- and micro-domains by cryogenic AFM and PDM
Journal of Microscopy, 2007Co-Authors: J-f Masson, V Leblond, J Margeson, Slaðana Bundalo-percAbstract:In an effort to better understand the structure and behaviour of bitumen in low temperature, we describe the first use of cryogenic atomic force microscopy and phase detection microscopy to characterize bitumen nano- and micro-structures. The results were interpreted in light of glass transition temperatures (T(g)s) for bitumen fractions. The domains visible by microscopy, the catana, peri and para phases, were attributed to domains rich in asphaltenes, Naphthene and polar Aromatics, and saturates, respectively. Between -10 degrees C and -30 degrees C, atomic force microscopy images revealed topographic features not visible in atomic force microscopy images acquired at room temperature. According to phase detection microscopy and T(g)s, the features were assigned to viscous unfrozen saturates. Upon cooling to -72 degrees C, unfrozen domains of 20-400 nm were observed. These domains were found in the paraphase rich in saturates and in the periphase rich in Naphthene Aromatics and polar Aromatics. The findings indicate that new viscous domains form upon cooling to low temperatures owing to phase segregation, and that some bitumens are never entirely rigid in low temperatures.
